1. Field of the Invention
The present invention relates to a sheet feeding apparatus for feeding a sheet used with an image forming apparatus such as an electrophotographic copying machine and the like.
2. Related Background Art
Nowadays, various information processing equipments have been proposed in dependence upon progress of information processing systems. Among them, recording apparatuses such as facsimiles, printers and the like have been widely used not only in offices but also in general homes.
FIG. 7 is a sectional view of a facsimile system to which a conventional sheet feeding apparatus is applied. A cassette 142 to which recording sheets (sheet materials) S are housed is mounted to a predetermined position of the facsimile system, and there are provided a recording sheet separating portion 143 comprising a pick-up roller 143a and a separation piece 143b which serve to separate the recording sheets S one by one, a sheet supply roller pair 145 comprising a pair of feed rollers 145a, 145b for conveying the separated recording sheet Sa, a recording portion 144 comprising a sheet feed roller 146 and an ink jet cartridge 147 having an ink jet head and an ink tank, and a sheet discharge roller pair 148 comprising a pair of sheet discharge rollers 148a, 148b for discharging the recording sheet S on which an image was recorded.
However, in the above-mentioned conventional art, in order to always contact the recording sheet stack S in the cassette 142 with the pick-up roller 143a, as shown in FIG. 8A, an intermediate plate 149 is always biased upwardly toward the pick-up roller. Further, an upper surface of a front wall 142a of the cassette 142 is positioned slightly lower than an upper surface of the sheet stack S.
Thus, if the cassette 142 containing the recording sheets S is mounted to the predetermined position of the facsimile system vigorously, as shown in FIG. 8B, several recording sheets S positioned above the upper surface of the front wall 142a of the cassette are advanced forwardly by inertia force, thereby forcing down the separation piece 143b for separating the recording sheets S one by one and entering the recording sheets between the pick-up roller 143a and the separation piece 143b to cause poor separation.
This is caused when separation pressure (contact pressure between the pick-up roller 143a and the separation piece 143b) for separating the recoding sheets S cannot prevent the recording sheets S from entering between the pick-up roller 143a and the separation piece 143b due to the great inertia force of the recording sheets S.